In situ electrochemical reconstruction of Sr 2 Fe 1.45 Ir 0.05 Mo 0.5 O 6-δ perovskite cathode for CO 2 electrolysis in solid oxide electrolysis cells.

Solid oxide electrolysis cells provide a practical solution for the direct conversion of CO 2 to other chemicals (i.e. CO), however, an in-depth mechanistic understanding of the dynamic reconstruction of active sites for perovskite cathodes during CO 2 electrolysis remains a great challenge. Herein, we identify that iridium-doped Sr 2 Fe 1.45 Ir 0.05 Mo 0.5 O 6-δ (SFIrM) perovskite displays a dynamic electrochemical reconstruction feature during CO 2 electrolysis with abundant exsolution of highly dispersed IrFe alloy nanoparticles on the SFIrM surface. The in situ reconstructed IrFe@SFIrM interfaces deliver a current density of 1.46 A cm -2 while maintaining over 99% CO Faradaic efficiency, representing a 25.8% improvement compared with the Sr 2 Fe 1.5 Mo 0.5 O 6-δ counterpart. In situ electrochemical spectroscopy measurements and density functional theory calculations suggest that the improved CO 2 electrolysis activity originates from the facilitated formation of carbonate intermediates at the IrFe@SFIrM interfaces. Our work may open the possibility of using an in situ electrochemical poling method for CO 2 electrolysis in practice.